Coating techniques which are performed in such a manner that nanometer- or micrometer-sized particles are aligned on a substrate so as to coat the substrate therewith, are required in a variety of fields. For example, such coating techniques may be applied to memory devices, linear and nonlinear optical devices, photoelectric devices, photomasks, deposition masks, chemical sensors, biochemical sensors, medical molecule detectors, dye-sensitized solar batteries, thin film solar batteries, cell incubators, surfaces of implants, etc.
A Langmuir-Blodgett (LB) method (hereinafter referred to as “LB method”) is well known as one such technique for coating a substrate with aligned particles. In the LB method, a solution comprising particles dispersed in a solvent floats on the surface of water and is then pressed using a physical process, thus forming a thin film. A technique using such an LB method is disclosed in Korean Unexamined Patent Publication No. 10-2006-2146.
In the LB method, however, temperature, humidity, etc., should be precisely adjusted so that the particles are self-assembled in the solvent. Further, surface properties (e.g. hydrophobicity, charge properties, surface roughness), etc. of the particles on the substrate may have an influence on the movement of the particles. Accordingly, the particles may agglomerate, and thus may not be uniformly applied on the substrate. Specifically, a large region of the substrate may not be coated with the particles, and grain boundaries may be formed at positions where the agglomerating particles come into contact with each other, resulting in many defects.